5 cups of crushed strawberries: I simply cut mine in halves and place in a strainer, wash and then place them in a pie plate and crush them with a potato masher. Some will use a food processor, but I don't do this because it tends to mess with the texture of the jam.
4 Tbls of Lemon Juice: This helps bring out the natural pectin in the fruit to help ensure your jam will set. Very important, do not skip.
1 pkg of Pectin: I use the surejell brand. I can't tell you the plus and minuses of all the different brands, I just know that this is the one I have always had success with so I stick with it.
7 cups of sugar: Yes, this seems like a lot of sugar, but remember this recipe makes roughly 8-10 1/2 pint jars of jam. There are also many sugar free jam recipes out there, but this is most definitely not one of them.
As you can see, I should be set for a while on strawberry jam as I was able to repeat this recipe three times with the amount of strawberries I got from the one flat. I heated the crushed strawberries until I got a nice rolling boil going over medium heat along with the lemon juice. Make sure you stir often to avoid scorching, making jam is a process that does not need to be rushed. Once you have a nice rolling boil, add your pectin and stir until dissolved. Once pectin has been completely dissolved you can add your sugar. It is very important to add all the sugar at once and not in stages. To help with this process, I usually premeasure my sugar in a bowl and set it aside until needed. Once you have stirred all the sugar into the strawberries wait until you are able to get a good rolling boil while stirring. Once this happens, stir for about a minute and remove from heat. Be careful at this stage and be prepare to remove it from heat if it begins to rise, which it has a tendency to do at times.
Once you've removed your jam from the heat, check to make sure that it is gelling, either with the fork test or the cold plate test. Before you start jarring you will also want to remove the foam that has accumulated on top of the jam. I find that a large serving spoon works best for this. Once you are sure that your jam will gel, place it in the jars that you have prepared and process via water bath for the appropriate time determined by your elevation. For more tips on the actual canning process you might want to check my link and videos I made of the process at this link: Canning Tips - Hot Pepper Jelly.
Canning and making jams and jellies can be one of those new hobbies that you can find to be difficult to understand at first. The best advice I can give you is to just try it. Experience is the best teacher especially with this hobby because it really is, as any hobby or artwork is, unique to the creator.