How to creep block basically?

1. Figure out what's the "Stop" key for you.
2. Click in front of you, steering yourself to walk in the way of creeps.
3. When creeps are right behind you, press Stop key.
4. Creeps stop as they can't run through you.
5. Start walking again straight forward.
6. Repet 2-6 until you've reached the lane.

For safelane, you can't really be pressing Stop key, since the creeps will move so fast that they are likely to run past you

For hard lane, the opposite is true, it's very easy to block them

The speed buff lane creeps get ends 15 seconds after the creep wave has spawned(0:15 in game clock), so when blocking hard lane creeps, that's when you need to start actually paying attention that the creeps don't accidentally run past you.

You can adjust how much you block by how frequently you stop

If you keep pressing stop key, the block is very strong. However, it's often good enough to just walk in front of the creeps and making sure they don't get in front of you. If your enemy doesn't block, you don't need stronger block than that to get the creep wave right under your own tower.

There's also an "easy version" of stop key blocking, that doesn't use stop key

You can do it with just mouse. Basically, you go in S-shape pattern. Walk straight forward in front of creeps, and when creeps are behind you, click little bit to the left, then a lot to the right, then back to the front again. This way you effectively stop for a second to complete kinda S-pattern, and creep behind you hopefully get blocked by your sideways motion. This S-like pattern is what replaces stop-key.