How to combine multiple devices into a stack?
In cisco it is possible
If the solution is in the wiki or on the forum, please give me a link.
I really need it!

There is no stacking feature.

Unfortunately stacking is not available with Mikrotik Switches yet, however you can find that feature with other switches (FS, Dell); and those ones works great with Mikrotik Solutions. We've developed lots of WISPs with those switches.