If you don't have a landmine device to put your bar into then you can always use plates or just a corner of a room. Once it's setup, you're going to kneel down on your right knee and your left knee is going to be up.
You're just going to rest your left arm on your left leg or down to the side. You're then going to take the bar into your right hand and start with it right at the top of your shoulder. From here you're going to press straight overhead and you're going to slowly lower the barbell back down to your shoulder.
One more time from here just press the bar straight overhead at about a 45 degree angle and then bring it back down to your shoulder. Repeat on the other side.