Doreen, there is an Alameda Social Club that promotes people to network
Here's an article about how it came about http://www.alamedamagazine.com/Alameda-Magazine/March-April-
And here's where you can see what event(s) are planned
Happily, Alameda offers so many activities ---- if you like to dance, check out Friday night Zydeco dancing class at Eagles (on Alameda Avenue, cross street Park St) http://www.sfzydeco.com/Eagles/eagles.htm
You don't need to have a partner just to go. Learn the basic steps first, and then it's dancing all night. Folks ask other folks to dance.
Try that first.
Or if you want to see what seniors do for fun, try Mastick Center http://mastickcenter.com/
They offer a lot of activities as well.
And since you have a small dog -- you may have noticed that people in the small dog park like to sit around to chat. Just join in. Once you mention you're new to town, they will likely offer all kinds of things to do. We have met some wonderful friends (in the big dog park) and we get together several times a year. We even have our Christmas party where we exchange gifts for our dogs.
Let me know what kinds of activities you're interested in, and I may be able to help.
Welcome to our beautiful island city :)