Frank, I assume you have installed the Fishsim2 simulator game on to your computer, to have the whatiff function working the easiest way is to ensure you have the latest 2.13f version update installed this automatically has the whatiff function built in and has a small window showing your actual float in it (easier than trying to see your float position on the screen) and also the species and weight of fish you have lost. To download v2.13f, clk on DOWNLOADS at the top of the forum page when the Downloads window opens, in the right hand side column open up LATEST UPDATE, on the new page clk on download this opens up the MEDIAFIRE window, clk on the green DOWNLOAD bar this downloads the latest v2.13f version to your DOWNLOAD folder on your computer. To install the v2.13f version to the simulator game ensure it is closed then click on the v2.13v exe file that you have just downloaded this will automatically install this latest version to your FS2 game. Open up to start fishing and you should see the BigFloat window on the top left of the screen.
To see what fish species are in the venue you are fishing, when you are actually on your chosen venue press the F8 key on your keyboard and this should show all the species to maximum weights in the venue, if not then you should download and install the latest species and graphics file from downloads, however see if the above works first!.
Frank that is as simple as I can make it, good luck and tight lines.