Your question is a bit complicated for this limited forum. You should refer to a French comprehensive grammar book.
Here are a few indications though.
"Présent" is quite clear : the action is being done : Je mets = I'm putting...
For the past, we have two tenses : "imparfait" : the action has developed in the past and has lasted a certain time. The stress is put on the process : "je mettais" = I was putting...
"Passé simple" = the action happened in the past at a precise time, but the stress here is put also on the fact that it's definitely over and done. "J'ai mis" = I put...
"Le futur" : the action will take place in the future. "Je mettrai" : I will put..
"Le conditionnel" indicates that the action will take place in the future, if required conditions are present. "Je mettrais" : "I would put...,IF..."
As to the subjunctive, check it in a grammar book, please !
Hope it helps anyway. Jean Paul