When you know Robo Miner from your mobile device (like a phone or a tablet) you may already know, that the Robot wil just move in the direction where you tap.
On PC this is fully equally but you use your mouse instead. If you click left of the robot, the robot will move a step to the left and so on.
Because we all know, that Robots are not able to jump (they just aren't) - you need to place ladders if you want to go upwards.
Ladders are built automatically, when you move upwards - as long as you carry enough of them. They get refilled automatically when you come back to the top to your UFO. You can increase your ladder storage by upgrading your robot at the UFO (just click the UFO to enter the Upgrade Store)
If you dig away the mud underneath a stone block, the stone block will start to rumble and consiquently will fall down. To prevent it from falling down you can place a pillar! The pillar has to be built on the top of another block. Even rows of pillars can fall down, so dig carefully.
To place a pillar you can click on the Pillar-Icon on the lower left of the screen or just hit Space!
Here is where you store your special Items like Dynamite! Dynamite is pretty funny, you can find it down in the question mark fields or you can buy it at the UFO. To use it, open your inventory (click the green thing in the lower left of the screen or press 'I') - select the dynamite and click OK. The dynamite gets placed and activated. Now get in a save spot and watch it explode. Be careful. Some blocks are pretty exlosive when under pressure, like Lava!
Hopefully this will give you a little start in how you can play Robo Miner - there is also an ingame tutorial, which you should check out. If you have any question, please leave me a comment!