There are lots of different punctuation marks and your teacher will show you how they are used, but at the very least you need to use full stops.
A full stop goes at the end of a sentence. Sometimes it’s tricky to know where the end of your sentence is, but read what you have written, and if it has a verb and it makes sense on its own then it’s a sentence. If in doubt, ask your teacher to show you.
Have a look at this passage and try to work out what is going on.
I took my dog for a walk with my friend yesterday he was late because he had to help his mom wash up before he left the house she didn’t know he was meeting me so she made him dry up too he forgot to tell her so she never found out in time we walked for miles we got blisters on our feet and achy legs when we stopped we had some biscuits when Rover finished eating his he licked my hand
It’s hard to understand, isn’t it? Have a go at putting some full stops in, and you will see how much more sense it makes.