File structure on server - where do I find threads

[twistsol]

You should find it in the database in the table "NODE"

If you look at the link you provided,

http://www.minibuggy.net/forum/projects-progress/19848-mini-raptor-k-fab-style.html

The number in the link to your thread 19848 is the nodeid for the first post in the thread.
Subsequent posts are also in the node table where the the parentid field in the node table = nodeid from your link above.

To get the first post

select * from node where nodeid = 19848;

To get the subsequent posts

Select * from node where parentid = 19848;

Note that this is based on VB5. I don't remember if VB4 or VB3 were different. Too old to remember and too lazy to look it up.