Textgram allows you to create Instagram-style images with text, custom backgrounds, and photos that you can then share through the app on Instagram, or you can opt to save photos locally and then send them from the Instagram app instead, if you prefer.
After installation, you can load Textgram and start creating images. It provides a short tutorial on the basics of creating text grams and then allows you to navigate the various options in the app on your own. You can add custom frames, load an image as a background, create effects for the background, or change the font, size, style, color, and shadow of your text. There is quite a bit here to customize your images and all of them are then Instagram-ready. The interface lacks any complexity with a fairly basic menu at the bottom, and everything loads and saves very fast so you can create and send these rapidly.
As a free app to provide additional options for what you post on Instagram, Textgram is a solid app. It doesn't have the depth of some other text-editing and meme-creation apps, but it works well with options you'll need for Instagram sharing and its speed and accessibility are perfect for the images you'll be creating.