1) Simply copy one of the existing Race.entity files...rename it and voila! then go into stirng file and add a line with PLAYERRACE_NAME .....then the name of file
Value "name of new race"
Simply open String and do CTRL+F and write PLAYERRACE.
Copy-paste the info (not forgetting to add +1 to total stirng count) and modify to fit your race.
2) in your newly created Race.entity...simply change the lines with the ships of the race you copied to the lines of oyur new ships which you will add to the gameInfo folder.
3) Again Copy-paste all tech trees for a race and adapt from those (ie.open file make changes so it does hte suitable effect...change its location ion tech tree).
4) Picures must be under Tgs format and be added to the "good question someone fill me in here" folder (I dont mess around with pictures..YET) then simply open the file of one of your entities and post the link of the image in its "image line"
Hope I helped...was a little rush of an asnwer cus I gotta go!