how can i just dig a hole for a well ?

[Gunsaremagic]

And how can i block or build a wall to block a certain area?

[McFuzz]

It's in the build menu, under Construction.
Hole for a well is under dig menu, in Channel. Just dig straight down.

[ViiK]

Originally posted by Gunsaremagic:

And how can i block or build a wall to block a certain area?

In previous version you could dig a 1x3 rooms on each level. Up/down stairs on 1 tile, empty space for the wall in the middle and channel down on the last tile. When all channels are done, build walls on the middle tile to block off the stairs. Just remember to not build a down stair on the last level before the water, so flying things won’t use your stairs to get into the fortress, otherwise you have to block it with a hatch.

[Gunsaremagic]

cool thx