Welcome to the forum.
6/8 against a general 2/4 is really quite straightforward.
- In the first bar use shift-M 6/8,4 (alt-enter) - this creates the independent time signature and keeps the bar length at 4 quavers.
- In the second bar shift-M 2/4 (enter) - returns everyone to the global time signature. You then hide it using properties.
- Now you just enter all the notes in the 6/8 part using tuplets. (There are engraving options to automatically hide the tuplet numbers and brackets for repeated tuplets).