Ah. A few purposes of fursonas are just a way to express yourself, roleplay, make a character for fun, or represent yourself as a sona, or to have an online avatar. those are just a few uses of em~ some people use one, multiple, or occasionally even none of them if they have another reason for having one.
If you ever wanted to commission a fursuit, that's another reason to have a sona!
You could write a description of your sona's look and other traits, and have an artist create it for you as well!
A sona for most furries is simply an extension of themselves - the way they would like to be, or how they'd like to express themselves!
If you've already got a species chosen, you're already farther then a lot of furs get right away!
Just don't rush it, take your time to create a character you'll be happy with, or different characters to represent different aspects of yourself!
For instance, I'm mainly a squirrel, but my secondary sona would be a skunk!
Just have fun with it, and be creative!