can any tell me how to merge tracks for roller coastertycoon2

If I've read your post right you want to merge two seperate tracks into one track right? If that's the case then I'm sorry to say that it cannot be done in RCT2. But you can make one coaster track act like two with side-by-side stations and either a mobius twist or crossover. The coaster train will exit from one station and then enter the other. This is a good design for racing and synced coasters.

Track merging can be done. You'll need a trainer such as 8 Cars or Son of Beast, and have to search for a tutorial. I've never done it so I don't know how it's done.

I've seen a tutorial for this somewhere, it allows, with use of the 8cars trainer, to merge together different types of coasters, so you got a loop in a giga, say. It looked pretty complicated though

It can be done with the use of trainers just like Leonardofury said. Your best be to find a tutorial is to check out the forums at New Element. You should do a search for this before you ask your question as NE isn't the most friendly place for new members. But if you do a search and still can't find what you're looking for, go ahead and ask. There are people there that will help you out. And if they can't help, they will try to point you in the right direction most times.

Be aware that the language there can be quite different than the rest of the RCT community.

I did see a how to guide at www.rct2.com

It was in the forums do a search and ya should find it.

There's also a tutorial at RCT Competitions under the hacking page. I myself couldn't follow this.