You could edit the Tab Order in Layout Mode and use the Tab key instead of enter.
"could I somehow push enter and move to the bottom field that is directly under the data that I am typing in !"
Yes, you can.
While in Layout Mode, select ALL your fields and:
Inspector > Data > Behavior > Go to next object using...
Welcome to FileMaker. The answer to your question will depend, in large part, on exactly what your data entry interface looks like and what you're trying to accomplish.
It sounds like, from your question, that you're familiar with spreadsheet programs like Excel and are trying to enter data in a method similar to how you might do it in that sort of environment. That is somewhat possible inside FileMaker, but not ideal, because FileMaker isn't really a spreadsheet program. It's a database environment.
Unfortunately, the default layout for a new database brings a new user up in Table View, which looks suspiciously like a spreadsheet, so new users are often confused into thinking it is a spreadsheet. Then then believe they can do things like "Fill Down" and are frustrated when it doesn't work. (Something of a pet peeve of mine; I'm not crazy about Table View for general use. Okay, rant over.)
Assuming I'm on track - that you are, in fact, trying to do spreadsheet-like entry in Table View - it is possible to have FileMaker go to the next record in Table View using a Script Trigger when you hit a keystroke (like an Enter). You can write a script that looks for that keystroke (which is either code 10 or code 13, depending on whether you're talking about "Enter" or "Return") and set it to fire using the OnKeystroke trigger when you're in the field. In this way, you can force FileMaker to move to the next "row" (record) when you hit that key.
Doing a "Fill Down" is a little more complicated. In this case, what you're looking for is the command called Replace Field Contents, which is located in the Records menu (in Browse Mode). This will cause FileMaker to replace the contents of the current field across all records in the found set with either the contents of that field in the current record, a serial number, or a calculation you define. Some things to remember about Replace Field Contents:
1) It affects ALL records in the current found set; there's no highlighting some number of rows the way you can in Excel. So perform a Find and get the records you want in view FIRST before executing it.
2) Replace has NO UNDO. None. Zip. Zilch. Nada. If you screw it up, there's no going back. So MAKE A COPY of your database before you execute this command, especially if you're new to FileMaker.
Given that, I would suggest that you learn a little scripting and, instead of using Replace, write a script that does this operation. You can then attach that to a button and execute it when you want to do these kinds of global changes. Why? Because you can write it, test it on dummy data, and then be much less likely to make a mistake later. You can include little warning dialogs that tell you how many records you're about to affect, so you can say, "Wait a minute! All 5,000 records! That's not right!" and catch it before you mess something up.
cdurham may be on manual mode,
In layout mode when you select a field there is a selection, Tab "Data" - Section "Behavior", for moving to the next field. By default the Tab key is enabled but you can also enable the Enter or Return keys.