I just beat the first boss in Tower of latria and there is no stone to continue to another section in this worl (I mean to go back to the Nexus and then be able to start from a second checkpoint). I beat the boss, got ressurected, got souls and everything, but there was no stone to touch so I backtracked back to the enterning so I could keep earned souls... there is still only one checkpoint when I touch the Archstone in Nexus.

Is this supposed to happen? Thanks.

Go back to where the boss was. Walk straight up to the altar. Then there will be a cut-scene. When the cut-scene is over, your character will be in the new part of the level.

Thank you very much!