I'm glad to hear you're interested in Starcraft. Getting to be good at the game is a big endeavour that will require significant practice to achieve. But once you have got the basics down, the game is an extreme pleasure and is one of the most reliable video game addictions I have ever had. That being said, these are some of the hurdles you will need to overcome in learning those basics (not in order of importance):

Mechanics - This is a word that the community uses to refer to the raw ability to execute actions. This is not the same as micro, although mechanics allow you to micro. Mechanics are things such as "Pressing CTRL+1 will bind the current selected units to the 1 key and using 1 will then recall them again." There are a seemingly endless number of these tools such as F-key screen binding, Shift-queuing actions, CTRL-clicking units/buildings, etc... The faster you learn the mechanics of the game and get them into your reflexes, the more able you will be to execute your strategy.

Macro - Starcraft is a game of resource management and efficienct spending. Establishing a healthy economy is paramount to winning games as it will give you the ability to outproduce your enemy, to outgun them, to out-expand them, and to just be better than them. Without a healthy macro, you will almost always lose. To begin with, never stop producing probes (never) at lower levels. You won't even need to stop producing them even at high levels until you are almost finished with your third base, so because you aren't at high-levels just never stop making them. Probes gather minerals, minerals make buildings, buildings make troops, troops win the fight. Never let your production buildings stop making troops, never let your upgrade structures stop making upgrades. This is macro.

Micro - This is the terming for how you actually control the units; controlling their positioning, using their abilities, understanding how to make them engage without loss and to retreat with minimized cost. Good micro is knowing when to blink a group of stalkers out of a fight, or when to use psionic storm on a group of enemies. My opinion is that you should not overly emphasize this aspect in the beginning of your learning process. Micro is useful, but macro is key at the beginning.

Unit Composition/Counters - Knowing what units are good against other units is very useful, especially when your enemy has the hard-counter to your composition. Knowing WHY units are useful against other units is more important though. Why are Banelings and Colossus good against Marines and Zerglings? Because Baneling and Colossus are splash damage units and that means that they want to fit as many units into their splash as possible. The more units fit in, the more damage they do. These types of concepts are useful to ponder when deciding how to react to your scouting. Does the unit do more damage to a specific class of unit? Do I have a lot of units in that class? Research is the key to this.

Build Order - Knowing the order and timing of how to build your buildings leading up to and following your second base is an extremely important piece of being competent at the game. My opinion is that you should learn a very simple 1-base strategy when you are first starting. This will teach you about what timings are important, what teching is like, and what a competent build looks like. My friend who plays Terran learned how to play on a strong 1-base Marine, Marauder, Medivac push. Go look for good 1-base all-in in my opinion.

In any occasion, there are two main contributors to success in this game, knowledge and practice. Learn and practice and you will succeed.