question about head space in bucket

Ok so i just bottled my first batch and pretty sure it won't be the best. been thinking of all the things i done did wrong. Well the list keeps going.

The most noticable problem i had with this batch is it made a mess. Foamed and bubbled all over the place. My question is this...

When the recipe states to add water up to 5 gallons, does that mean i am using 5 full gallons of water or am i just topping off the wort to the 5 gallon level?

I think i used a solid 5 gallons of water, which might be why i made a mess. Also i guess that will dilute my beer. Am i on the right track with that line of thought?

If it's a 5 gallon batch then it'll be top off to 5 gallon.
If in doubt use a hydrometer to measure the gravity.

gosh simple enough. Good deal and thanks.

Ha ha! I am currently working on my first brew (in fact, tonight is bottling night!), and that was the one mistake I made. I didn't top off to 5g, but instead added 3g of water after having made a wort solution with 2g of water. Due to the fact that I dumped about 2 quarts of malt extract into the wort, the final amount of liquid in the fermenter was closer to 5.5g than 5. This isn't a huge problem though.

I am figuring that the only consequence of this will be that the final product will be a bit lighter and lower in abv than it would have been had it contained less water.

Advanced brewers, correct me if I am wrong here