Players have problems with controls in AYB, that`s priceless feedback and here is small manual:

First clicked planet is the source (blue marker).

Second clicked planet is the target (red marker).

To send ships click the source-planet and then click and hold the target-planet.

Note: you can send ships from one source to multiple targets, but you can`t send ships from multiple sources to the one target. Source marker will disappear when the last sent ship will reach the target, then you will be able to choose another source.

Note 2: you can`t send ships from your base to enemy base directly. Use neutral planets.

Advice: keep 5-10 ships on your base.