Yasg is short for Yet Another Simple Gallery. It cannot get any simpler than that - imho.
After plugin installation - all is left to do is creating a new gallery: Go to the admin area => Posts. Create a new post. Fill in a title for your page and set it in the right category. Hit 'publish' to save your changes. Once the page is refreshed, click on the upload/insert media icon above the editor's window. In the box that opens use the file browser to browse for the right photo from your computer and upload it. Repeat this for all your photos. Once done - click on the 'Gallery' tab, to view all your photos. Scroll down and hit the 'insert gallery' button. Hit 'update' to save your post.