Hi Devine,
The easiest thing to do is to Edit the Post that you want the Gallery on and add this shortcode in it where you want the gallery to be:
[photosmash]
With that, you should see a gallery and an upload link when you view the post. After you view it the first time, you can go to Gallery Settings and start tweaking it (select it from the dropdown and click Edit). It won't exist until you view your post the first time.
To set it so anyone can upload:
1) Add the shortcode ( [photosmash] ) to your post
2) View the Post
3) Go to Gallery Settings in the Admin
4) Select your gallery in the dropdown, click Edit
5) Go to Uploading tab
6) Select the Minimum role you want to let upload....Subscriber is the lowest logged in role...Anybody let you upload even if you're not logged in
Hope that gets you started.
Byron