To be able to work with your logo files you will have to use an image editing program. There are a lot of image editing programs around. Some you have to pay for, some you can download to your computer for free, and another option is to use an image editing program online. On this website I am using two image editing programs in each tutorial:
Adobe Photoshop & Photoscape
>>> ABOUT ADOBE PHOTOSHOP
Adobe Photoshop is professional image editing software. I use it to create all my logo designs. It's a fantastic program, but not a free one. You can buy the complete program from Adobe or sign up for a subscription program, but either way, it is going to cost money.
Since a lot of my logo designs are created for photographers, a big part of my clients will probably have access to Adobe Photoshop already. Therefore I will show all tutorials with Adobe Photoshop as well.
And for the clients that do not have access to Adobe Photoshop, there is always the possibility to download a free 7-day trial of the software over here: http://www.adobe.com/products/photoshop/free-trial-download.html
>>> ABOUT PHOTOSCAPE
If you do not have access to Adobe Photoshop and you are not planning to spend any money on image editing software, then you can use Photoscape. It is the software that I once started out with and although Adobe Photoshop is much more versatile in what it can do, Photoscape is still amazing considering it is free.
You can download Photoscape for free over here: http://www.photoscape.org/ps/main/download.php
No matter which of the two options you select: the free Adobe Photoshop trial version or Photoscape, after downloading the programs you will have to install them on your computer/laptop before you can start working with them!