Alright here you go. I'll just write a guide.
1. Make sure you have Winrar
2. Go download the client.
3. Save the Zip/Rar to your desktop
4. Right click the file on your desktop and select extract here
5. Wait a few seconds.
6. You should get a folder that is called Romescape.. I Think.
7. Open the folder, scroll all the way to the bottom, or just look for the cmd promt file name Run
8. Once you find "run" double click it, wait a little bit, then the client should load.
9. A familiar log in form should be seen.
10. Sign in with whatever username and password you like.
Hope this helped. Good luck m8
* - FTF