Appearance
BPM and Time Signature
Initial BPM and time signature
BPM and time signature changes are visible in the gutter between the top menu and the player tracks. The initial BPM and time signature are located at the start of the track and can be modified by double-clicking on the marker.
Adding markers
Additional markers can be added by clicking anywhere in the gutter. They can also be moved around and deleted much in the same way as notes.
Editing markers
Changes in tempo (including the time signature and BPM) can be placed by clicking on the gutter between the editor navigation and tracks. Double-clicking on the change marker will open a window allowing you to change its values. With the exception of the initial tempo marker, all markers can be dragged and repositioned as needed.
Resources
If you aren't sure what the BPM or time signature of your song is, I suggest looking it up on a site like GetSongBPM and SongBPM.