MinimalStress 0 Newbie Poster

Hey guys, my name is Ross. Im new to programming and i need some help with assembler. I have a menu with a number of options that the user can do.
1. The first one is the user must input a string of characters up to the limit of 25 and then give a error message. i can get the menu done with the input but i cant seem to get the error message.
2. The second option is to display the string inputted by the user, which i have done, so no problem there.
3. I need to display a count of punctuation marks in the inputted string, which i have no idea how to do, so need major help on that as well please.
4. Reverse the string, which also i have done so no prblem there either.
5. I need to replace the consonants with '*'s which i also dont no how to do. please help with this too.
6. This is an extra option which is a caesar cipher which i cant do as well but it is not needed right now..
and then the last option is to exit which i have done as well..

If needed i can send u the program which i have started as it may help you..

Inno there is a lot of work needed and would very apreciate any responses..

Thanks,
Ross