I will let you know how most tiers sell there flies
You got go to some local fly shops in your area (the mom and pa type)
Show them what you can tie and ask if they are in need of any special pattern tied and how many.
Tie up some of the flies they are in need of, most of the time if it is tied good enough they will buy the flies outright from you
Give them your card and have them call you when they start running low on the patterns you tie.
Most fly shops are going to want to mark the flies up to make 100% profit so you will have to price your flies accordingly
For instance if the fly shops can sell your flies for $1.50 each he will want to buy them from you for .75 each
The only other way is to sell them for yourself from a web site or on Ebay.
I know its a sad state that American fly tiers find ourselves but the fact of the mater is that in order to compete with flies tied in Malaysia and china a tier can only hope to make Minimum wage tying and thats if there good at it.
Thats why I got out of it years ago ( my time is worth more to me then 5 dollars a hour)