Problem with Comments

Being new to blogging I am still feeling my way around. I posted an introduction to a theme, then tried to add eleven Comments to complete the theme – the first ten worked ok, but the eleventh did not load, it completely disappeared when I tried to load it, and when I tried a second time it threw up an error message “You have uploaded this one before”. I notice in other blogs there are numbers at the bottom of the ten Comments – 1 … 2 … 3 … 4 … 5 … etc to take me to more Comments on another page. My question is, how do I configure my Comments program to enable me to continue with other sets of Comments in this way? I hope all this makes sense, but I did say I am new to blogging.

[PS – unixgolf need not answer this]