Depends on how you want to merge (adding records or adding fields),
whether curs1 and cusr2 are updatable and whether they have the identical field structure.

Let us suppose you want to append records from curs1 to curs2 and both cursors were created as /create curs.../ and they have the very same field structure. Then you may use something like:
sele curs1

=field(afld)
create curs curs3 from array afld
append from curs1
append from curs2

>i have two cursor
>cursor1 and cursor2 and i want to merge them into cursor3
>how