Policy slot.

[Friend]

How do I fill it? Where is the place to?

[Metadragon]

In the upper left corner there is a series of buttons. its one of those. Some civs have special versions like America who converts its diplomatic policies with wildcard ones

[Imhotep]

It's the one that says 'Civics' when you mouse over it.

[plaguepenguin]

The Government button, third from left in that row in the upper left corner, is the one that brings up the screen where you can fill your available policy slots with a combination of your choice from among the policy cards you have researched. There are three tabs in this screen. The Change Policies tab is the one you want for this purpose.

You can get to the same screen by pushing the Change Policies button at the bottom of the card that pops up automatically announcing that you have finished researching a new civic that turn.

You get an opportunity to shuffle your policy cards in or out of your slots for free on the turn you finish a civic. If you hit Change Policies at the bottom of the civic completed box, when it takes you to the Change Policies screen the policy cards are all available for shuffling. If you get to the same screen by using the Government button on some turn on which you didn't finish a civic, the policy cards are visible for inspection, but grayed out. To unlock them and make them available for shuffling on such a turn you have to hit a blue button that appears below the cards and pay a hefty fee in gold.

Unless you face a real emergency and have to shuffle policy cards immediately, the fee means that you plan ahead to make all your needed card shuffling happen on a turn you don't have to pay the fee.

If you are about to finish a tech that unlocks unit upgrades for example, and you need to apply those upgrades as soon as they become available, you would plan ahead and on whatever preceding turn you finish the last civic, you put in the card that gives you a discount on upgrades. After you do all your upgrades, the next turn that you finish a civic you could replace the upgrade discount with the card that lowers how much each unit costs per turn to maintain.

[Kaycha]

Sounds like potential mod problem if nothing shows up when you click. Do you run any mods?

[Imhotep]

Here's a Youtube video of someone clicking on the button (at 0:58), which is called 'Government'.

https://www.youtube.com/watch?v=OIDyhUJU-eI&feature=youtu.be&t=56
Drag the cards to the slots and click 'Assign All Policies'. You can only change them for free when you complete a civic.

[tempest.of.emptiness]

Also, consider playing through the tutorial. If you are having trouble figuring out how to slot a policy card then there are probably going to be many other questions that you'll have, and the tutorial may answer a lot of them.

[Dray Prescot]

When you finish a new CIVIC, you will be offered the chance to change governments and Policies.

1) Left click on the Government button which is the on the 2nd row from top of screen, 3rd item from left.

2) Left click on Change Policies underneath Government on the top center of Screen

(To Change Governments left click on the Change Governments button.)

(Left click on My Government to view your current Government.)

this opens a Window on the right with all of the Policies that you can currently select, the scroll wheel on your mouse will enable you to shift the Policies window if it is too wide to fit on the screen

3) Look at the Policies and their descriptions of what they do, when you find a Policy that you want, put the mouse cursor over it and then Left Click (mouse button) and HOLD the left button down while you DRAG the Policy to the left where you want it to be. It has to match, a Military Policy in a Military Policy Box, a Economic Policy in an Economic Policy Box, a Diplomatic Policy in a Diplomatic Policy Box, and at the bottom they may be (with a good enough government) a place for WILD CARD POLICY(s), these will take any type of Policy.

4) Click and DRAG any more Policies that you want to change to take affect for your Civilization.

5) When you are done, left click on the Assign Policies and you are done, until the next time you get a new CIVIC, when you change governments and Policies again. You may also be asked to CONFIRM that these are the Policies that you want. Left Click on the Confirm Button.

If you try to change Governments or policies on other turns (when you did NOT get a new Civic), there will be an additional money cost, and possibly a period of disruption when changing governments, particularly when going back to an old government that you tried in the past.

https://steamcommunity.com/sharedfiles/filedetails/?id=1975337115

Please read my comments on the screenshot while you are looking at it.