You can read all about it at http://althistfiction.com/current-issue/. You'll find information about how to get hold of a copy and also free previews of each story.
Here's a bit more information:
The third issue of Alt Hist includes two stories about the American Civil War, one about the great Tesla, a tale of post-war revenge set in Dublin, and a compelling story about the early years of the space race.
Full list of stories and authors:
A Light in the Darkness by Ian Sales
Dublin Can Be Heaven by Séamus Sweeney
Riders on the Storm by Arlan Andrews
Bummers by Matthew Warner
To The Stars by Brooks Rexroat