It sounds like you're starting a tubular structure, like a sock. You make sure the chain is long enough (enough stitches to go around your leg or whatever) and bring the last stitch with the hook back to the first one. If you're right handed, it will probably be esier for you if you make sure that the yarn feeds in from the inside of the loop that is being formed.
Put the hook through the first stitch again and draw the yarn back through it AND the last stitch then keep on going through the previous stitches.
Really, it is just as if you didn't reverse at the end of a row and put another row of stitches on top of it, but just drew the yarn back to the starting point and continued putting more stitches on tlp of the original one without having a reversed row between them. (I hope that's not too confusing.)
Just keep spiraling up until the tube is as long as necessary. You can add or subtract stitches to make the tube wider or thinner. If you are making, say, a shirt, when you get to the underarms, make two loops )one for each arm hole) and fill in rows between them. When you get a little higher, then you can make a neck hole and fill in the yoke.
If this isn't clear enough, try looking at a book with illustrations. Or ask someone who knows how to demonstrate. I wish you were here, so I could show you.
9 MAY 08, 0400 hrs, GMT.