Lookup & Cross Match

I am trying to create a project on excel in which there exists four worksheets. I deleted "class 2-4" due to file size but are very similar. My question here is i need a macro to located the number from the "current" column in the Manual Input section in the "Main Page" worksheet. The current number must match column A into the appropriate sheet (depending on class) and then look for the volume in row 5 and then round up to the nearest number. My goal is to input the "proposed" number into the appropriate column and row. This will be done for four different classes. My goal is to develop this table so that i can look for trends.

Eventaully i would like to concatenate multiple proposed values for each cell as the macro will need to add onto what is located in the cell should the value already exist. Code must be a module so it runs when ever data is entered in the current, proposed, and volume cells in the manual input.