Easy question with an easy answer.

First, download Audacity (a music editing program) from
here.
1) Once you've got the .exe and zip files, start up Audacity.
2) Open your mp3/.wav/whatever music file you wanna edit.
3) Click on the area where the sound is displayed visually (like multiple blue waves), and find the area where he says "Dre".
4) Right at the part where he begins to say "Dre", highlight the area where he says the "D" part.
5) Delete the "D" part of the music, til the "re/Ray" part.
6) Repeat for everytime you need the "re/Ray" effect. Listen if it sounds smooth.. if it doesn't sound right, i'm sorry.
You can also do this in Premier if you have it, using steps 2 thru 5. Hope this worx! @_@ Personally, I only edit music by putting in fades or by making it shorter.
Sayonara!