I'm just gonna throw out some suggestiions. They are not sorted in any specific order.
1. Get a TS channel
2. Work out a draft for how you want the regiment organised. Ranks, units, trainings, battles, rules, what kind of regiment you want (line, cav, skirmish, arty), etc.
3. Get some members. Perhaps you have some friends that is interested?
4. Have fun (most important one)
I wish you luck.