Actually, at this point, the internet is a terrible place to try to find reenacting units, especially Confederate ones. No one wants to deal with the trolls that an accessible website brings. FB is hardly better as most groups are closed groups so you need an in to get approved for membership. Honestly, advertising for a unit here, a moderated forum, is one of your best options. The other is to go to a reenactment as a spectator and start networking in person. Your musket will be welcome in almost any unit, and is a major purchase, so I think that was a good place to start since you have the $$. Assuming from the get-go that you´re going to rule out obviously unsafe and inauthentic (farb) units, There are some other questions you´ll want to think about before you join a unit: a) How far do you want to travel away from home? 2hours? 4? etc... b) what style of reeacting would you like or will your health tolerate? Campaign style - pack it in on your back, sleep in a shelter tent and eat out of your haversack? or more mainstream - A tent and cot if you like, eat on the local economy if you wish? Confederate uniforms and equipment vary wildly from state to state and group to group. More progressive, history-heavy units will have specific patterns for sewing and specific vendors who cater to their style and units. Leaning more mainstream, you may find groups that will (for instance) accept the uniform ¨package¨ from a well-known vendor as perfectly suitable for their activities. c) how open are you to galvanizing? (The practice of portraying either side as the unit feels is appropriate.)
It´s kinda near the end of the season at the moment, so your chances of getting out to an event may be limited. I´m nowhere near Mississippi, so I can´t help you a bit. There are good Confederate reenactors in this forum, who will be able to hel you network more than I can, but these are questions to think through before you select a unit. (There´s nothing so miserable as a mis-match between individual and unit expectations.