More than one transaction at the same time

Hi All!

Can I start 2 or more transactions simultaneously?
Task is in the following: I am startig transaction with the "begin",
then declare a cursor. Then I need to start another transaction in order
to do some things, but I don't want to close first transaction because
later I need to fetch frome created cursor.
Or I understand something wrongly?

Sincerely yours, Yury.
don.web-page.net, ICQ 11831432