This part of the guide can be done just by looking at the pictures, but be sure to read anyways for clarity!
To keep it as simple as we can, use the Mk1 Command pod.
One of the key ingredients in a good asparagus is to make sure it stays straight, so be sure to add an AdvancedSAS.
Many different tanks can be used as the center of the asparagus, but the Jumbo-64 will provide the best results for beginners as far as understanding how asparagus staging actually works.
Now in the current version of KSP (0.20), the Jumbo-64 tank on top of the engine we want will overheat the engine before it can get very high at all. So we will need a smaller tank below it. Just grab the smallest Rockomax brand tank and stick in underneath the Jumbo-64.
(Important: As of version 0.20, a strange wobble will occur causing the rocket to become difficult to stear when these 2 tanks are placed in this fashion, so until this is fixed, add Strut Connectors to hold the Jumbo-64 firmly against the smaller tank.)
Now that that overheating problem won't be an issue, we can now attach our Mainsail engine.
This is the center of our asparagus, from here on, it is crucial that your symmetry mode is set to 2.
Any of the radial decouplers will work, but the TT-70 will provide the most distance from the center.
Now we need to set up our 6 outer tanks, we will do this by keeping our symmetry mode on 2 so we only ever end up having to attach these parts once. Place a FL-T800 on the center of your decoupler.
Though there is a more effective version of asparagus staging, it can create problems with decoupling, so we will just be using the LV-T45.
Now to save (a lot of) time, we are going to copy our outer rocket (and decoupler) by pressing your respective operating system's modifier key, and left clicking on the decoupler.
Doing this will give you an exact copy of what ever you click on, as well as the parts branching away from it. Make sure your symmetry option is still set to 2, and paste your copies to match the pictures.
You should now have 6 rockets symmetrically placed around your jumbo. The last parts we need to attach are the fuel lines that make this rocket have its efficiency. Place your lines to match the picture (be sure the lines are facing the correct direction.
Our rocket is now finished, all we need to do now is set up our staging and we will be ready to fly.