Do you have any modding experience? Did you go through the Sins Mod Set? This is a PDF included with Forge Tools that I converted to a web page. This is a big undertaking for the novice.

I recommend getting notepad++ to edit files and other mod tools and reference files on the Modding Tools page. Using notepad++ practice learning "Find", "Replace", "Find in Files". Start with String\English and search (in the reference files directory) for TEC and see the lines it has for that race. Copy them to a new document. Once you edit these lines to fit your new race you might want to add a string like this was

StringInfo
 ID "IDS_PLAYERRACENAME_TECH"
 Value "TEC"

My new race is Bentuzi so I add a string

StringInfo
 ID "IDS_PLAYERRACENAME_BENTUZI"
 Value "Bentuzi"

Then I change the count at the top +1 to add the new string to the count.

Then I would use "Find in Files" IDS_PLAYERRACENAME_TECH to see which file links to that string and you will find PlayerTech.entity. Copy this file and name it to your new race like

PlayerBentuzi.entity

This file will link to the meshes sounds, research and such. This entity has to be added to the entity.manifest and the count changed +1. Any new file added to the GameInfo folder has to be added to the manifest and the count changed.

Now you want to find all the files that link to PlayerTech.entity again using "Find in Files" I do a search for PlayerTech 
which 1 will be GalaxyScenarioDef.galaxyScenarioDef

There are many different files you will need to modify to fit your new race in but this will hopefully get you on your way. Use the "Find in Files and search the reference files for Tech, PlayerTech and TEC. Some files will need lines added and others will need to be copied and modified.

Start off with this making COPIES and BACKUP all modified files and make your new mod folder and constantly test with the DEV.exes. See the SoaSE Modding Weebly