Hope this help.
First you need to make certain that you have the correct information Stina Casja was born in Tannåker not in Annerstad. Lars Petterson was born in Angelstad.
see attached records for Stina Casja.
Tannåker AI:5 (1840-1847) Image 19 / page 10 (AID: v19418.b19.s10, NAD: SE/VALA/00370)
Tannåker C:2 (1788-1859) Image 57 / page 105 (AID: v32418.b57.s105, NAD: SE/VALA/00370)
the once the info is correct you can do 2 things. (1) Search ancestry trees an look for families that resemble yours. Contact the people who are making the trees. (2) join Disbyt for sweden ( http://www.dis.se
) upload your tree to their site. The once this happens you will be able to contact the people that have trees with people in them.
Both have worked well with me.