Can anyone explain the info given in Analysis mode?

I use shredder chess on my iPhone and I noticed that it has an analysis mode. I'm a beginner so I'm sure this would be helpful.

I don't understand though all the information it gives you -

i.e. Value +0.23 what does this mean?

I presume the other notation are other moves that could be made?

How do you tell from looking at analysis information whether the moves you made were good or bad?

Most engines will reduce a position to a numeric score. Positive is good for white, negative is good for black. Usually measured in pawn units, so if you win two pawns the value will be close to +/- 2 everything else being equal. If you have other positional advantages, or an imminent fork coming, the score will reflect that too though.

If you're white and the engine proposes a move with a value that's significantly higher than the value you get from your move, your move wasn't as good as the proposed one.

"Value +0.23" means that White is ahead by a value of almost a quarter (0.25) of a Pawn. Value + 1.0 would indicate that White is a full Pawn up. Value -2.0 shows Black is ahead by two full Pawns of value. If you are White and have +0.23 now and after your next move you have maybe +0.28, your position improved slightly. If the number gets smaller or turns negative(-) you made a poor move.