Firstly, you need to know the tools and its options.
There are many features existing in Photoshop Toolbar in the effort to edit so you can represent the optimum image in any occasion.
The toolbar options can help you to erase, paint, add text, blur images, or make selections and others functions you can find.
To make you easily access the Photoshop Tools and the options, you can make it visible on your screen.
First, click on the window menu and then find Photoshop Tools and Tools Options feature, check those features to allow it display on your screen.
After successful display both features on your screen, you can learn the name and each function by pointing the mouse cursor on its symbol.
The next step, go to the Tools' options and find the Aspect Ratio feature.
In this feature, you can set the paper size that is going to be used in printing the picture.
After you have already format it, you will notice that the Crop tool feature becomes the particular aspect ratio.
At once you crop from this feature you can adjust the picture's print resolution as you desire.
When you open a picture in Photoshop, you will find the magnification has been reduced, so you can see the whole picture.
Being able to see the full picture will help you to edit it easily, then if it is opened in high resolution or 100% magnification.
However, sometimes you will need to the function of Zoom because it enables you to adjust or cut the picture's size on the screen.
After you display the entire picture on your screen, you can modify it easily.
You can cut the unnecessary part from the picture and enables to fit the picture on its canvas or frame by aligning it.
All of these functions can you reach on Photoshop's crop tool available on the toolbar.
Choose one and decide where the picture should start by clicking the area.
In order to remain some part within the picture, drag the box around the particular part.
However, if it is unwanted anymore, you can just push the ESC button and start it again.