G'day valerydolce,

Here's the steps you need for each line.

1. Match the start of the line.
2. Match the first / and everything up to, but not including, the second /.
3. Match a / followed by DUMMIES (one or zero times with no backtracking).
4. Match a /.
5. Start capture.
6. Match anything that isn't a / (one or more times non-greedily).
7. End capture.
8. Match the end of the line (before newline).

If the match was successful, $1 will contain 'user1', 'Dummy1', etc.

There a number of ways to implement this. I'll leave you to choose whichever you want.

Information on how to do everything described above can be found in perlre.

Update: I made the final step a little more specific by adding "(before newline)". Also fixed a typo: s/with contain/will contain/.