Compressing vocals on REAPER?

[Shine]

After following Cdra's tutorial about equalizers, and since I'm using REAPER, I would love to know how to use the  compressors!
I'm justr trying things while mixing a song with three singers, and in parts, when they sing together, the volume seems to loud and inconstant, or the voices unclear and oddly loud.
Does this has something to do with Compression or Equalizers?
Please let me know, I REALLY REALLY NEED to understand this, specially for this song, it's a very important project for me.

Thank you!

 

[Yue Nagareboshi]

REAPER has ReaCom.

You can find how to use it from this tutorial:

[Tutorial] Mixing Vocals into Instrumentals

He uses and old version of REAPER, but ReaCom has been the same all these years.

 

[Shine]

Thank you! It's very helpful. ^^