How can I migrate my computer redmine to aws lightsail?

I'd suggest taking a look at Redmine wiki/forums, e.g. this wiki post might help: https://www.redmine.org/projects/redmine/wiki/HowTo_Migrate_Redmine_to_a_new_server_to_a_new_Redmine_version

Essentially it'll involve migrating your SQL database to the new server and copying over any other data from your local Redmine installation to Lightsail, but the process can vary depending on the data you need to migrate and how much downtime you're willing to tolerate.