Hi DeltaVenom, welcome to the forums
luckily for you, these questions have been answered many times, and by many different modders here. This is a good time to make full use of the search tool, and I'll point you to a few helpful threads to get started.
At the top of the Holowan Laboratories page (above the threads) there is a list of tutorial pages. For adding new heads, I'd suggest looking in the Tutorials: .2da Editing
pages. For what it sounds like you want to accomplish (adding a new playable alien and portrait, right?), you'll want to pay attention to threads dealing with heads.2da
Another good place for starter info is the Tutorials: General Tutorials + Tools
page, in particular the four threads that have been stickied to the top of the list.
For an example of how to get playable Wookiees into K1, check out my list of Completed Mods
, which has several playable aliens, including Wookiees.
Once you've had a chance to look through several tutorials, and you've tried playing around with them, you can always ask specific
questions. Don't forget to specify if you are modding K1 or TSL, because there are some slightly different ways of going about things in each of the games (for example; Hex editing models is more important in K1 than TSL).
Anyway, good luck, and don't forget the search tool