How can I allow files to be added to posts and topics?

Ho can I allow files to be added to posts and topics? for example if a user has an issue and wants to share a log file??

Hello, Paul! Welcome to our community. Look for the upload button on the composer, or just drag a file into the composer window to upload. If you spend a bit of time participating in a discourse-powered forum or do the @discobot interactive tutorial you’ll get to learn about many useful features like uploading.

If you want them to be able to upload log files you’ll likely need to edit the authorized extensions site setting to add whatever file types are appropriate.