Help with pagiation

someone please help me…

for hours now i have been trying to sort out this problem. its something that i have seen so many people on the internet having but i cant seem to find the solution for it..

im trying to get a a page that will display all posts in a certain category and for them to also be able to click “next” to see the rest of the list on the next page…

Ive used the query post thing to get the list of the categories on my page but when i click “next page” it will display the same posts as page one. Im sure it recognises how many posts i have because of the multiple pages i have made for each category it displays a different amount of pages

Ive read up so much about the wp_pagenavi plugin and im still having problems with it due to me not being that experience with php coding

Could someone please tell me step by step on how to display all posts in a category on a page WITH the ability to click next page to see more posts

to see what i mean go to my site http://midnightreview.co.uk and click on any of the pages (not home page). Youll notice that posts are there but click “next” wont give you any new posts

Thank you all in advance