Need help on how to say sorry

[Elderp]

Conichiwa watashi wa Pedroza, John desu. Washi wa California.

Sumimasen, my Japanese is horrible but I am having fun learning. Anyhow, I was wondering how would I say that I am sorry. I know the word for excuse me is sumimasen but say I was in a situation where I was trying to talk to someone and for some reason I messed up the conversation I would like to be able to say.
"Oh Sorry, I didn't understand what you were saying." or another phrase I would find helpful would be "That is not what I meant." Or how about "Excuse me my Japanese is really bad." I would also like to learn. "Sorry, I will do better next time" or "Sorry I am still learning."

Domo Arigato for your show. I really enjoy it. I just started listening a few days ago and I have allready learned so much. These topics might have allready been covered and I haven't gotten up to speed yet. If so again sumimasen, just tell me where they are and I will try and learn the phrases.

Sayonara

[Jason]

Sumimasen, my Japanese is horrible but I am having fun learning.

Hey, we all started like that. So don't feel bad.

"Oh Sorry, I didn't understand what you were saying."

It might be better to simply ask them to repeat themselves:

"Sumimasen. Mou ichido (yukkuri) onegaishimasu."

yukkuri = slowly. If you don't necessarily want them to say it more slowly, you can leave it out.

"That is not what I meant."

"Iie, chigaimasu." Which is just a general phrase for, "no, that's not right."

"Excuse me my Japanese is really bad."

You could say it literaly:

"Sumimasen. Watashi no nihongo wa sugoku warui desu."

But it would probably be better to say:

"Sumimasen. Watashi no nihongo wa madamada desu." Which means, "I'm sorry. My Japanese still has a long way to go."

"Sorry, I will do better next time"

"Sumimasen. Kondo chanto shimasu." (lit: Next time I'll do it right)

"Sorry I am still learning."

Perhaps:

"Sumimasen. Watashi wa mada shoshinsha desu." shoshinsha = beginner