Im Not Sure If This Is The Right Place To Be Posting This, But

Since NetSeal Has Shut Down,

Im Wanting To Make My Own Version Of It,

Where Would I Start Off?

Any Help Would Be Much Appriciated

You would need to make a secure login system on a server with bans, hwid check, etc. (this is what the login system on tools would call too)
You would need to make a nice login/register system in multiple lang (thats if you want too, the more you support the more users will use your service) C# and VB
You would need to encrypt your code highly (don't use free crappy encrypt that can be cracked in 2 seconds)
Have people test all security flaws. See if people can bypass the login, spoof hwid check, etc.

Have fun, Goodluck

Would you be willing to help me out a little?