Choose File > New to create a document.

Note: If you intend to have your pattern printed as a textile, choose a manageable dimension for a tile, such as 4 x 4 inches, and set the Resolution to 300 pixels / inch. Choose CMYK color for the Color Mode and press OK.

Start by finding an interesting image that would work as a repeating pattern. If you want to recreate a textile like Leah Rama's find a classical portrait. You can find lots of open access portraits at NGA Images.

Copy and paste or File > Place the image you've chosen onto your canvas.

Click the Quick Selection tool in your toolbar and drag over the area of the image you want to cut out. Hold down the Option/Alt key to subtract from your selection.

Choose Select > Refine Edge and manipulate the Adjust Edge controls to clean up your selection. Click OK.

Finally, click Add Layer Mask in the Layers panel to isolate the selection from the rest of the image and make the background transparent.

Choose Layer > New Adjustment Layer > Hue / Saturation, and then click OK. Adjust the settings in the Hue/Saturation panel to brighten the colors.

You can also apply other adjustments to get the effect you want. For instance you can apply the Filter > Pixelate > Mosaic to get a pixelated look. Make sure you select the image thumbnail in the Layers panel before applying filters.

Tip: Leah achieved her pixelated effect by duplicating the image layer and applying the Mosaic filter. Then, she masked out parts of the pixelated layer to reveal the original beneath it.

Now that you have artwork, you can save it as a graphic to your Creative Cloud Libraries and use it in Illustrator to create a pattern.

Choose Windows > Library. Then Select all visible layers in your Layers panel. In the Libraries panel, click Add Graphic. A new graphic thumbnail appears in your libary.

Tip: Repeat steps 2-5 any number of times to create a wide variety of graphics to use in your pattern.

To recreate the textile designs in this tutorial, copy the Pixel pattern library to your Creative Cloud Libraries. Click Save to Creative Cloud to create a copy of the files in your own account.

Once in your Creative Cloud Libraries, you can use these assets as patterns and images in your documents in Illustrator or Photoshop.

Launch Illustrator and create a new document with the same specifications you used in Step 1 (4x4, 300 ppi). Click Advanced and ensure the color mode is set to CMYK.

Choose Window > Libraries and choose either your default library or the Pixel pattern library. Select the graphic thumbnail you created and drag it onto the artboard. 

Click the Embed button in the Control panel at the top of the screen to add your artwork to the document.

Add several objects from your library to compose a pattern tile, rotating and scaling graphics as needed.

When you're happy with your tile, select all the graphics in your artboard and choose Object > Pattern > Make. The Pattern options dialog opens and a new pattern swatch is automatically added to the Swatches panel.

In the Pattern Options dialog, give your pattern a name and experiment with Tile Type settings. 

Change the Overlap setting to see what kind of effects you can create. Click Done. Your changes are applied to the new pattern in the Swatches panel.

Now that you have a textile, you're ready to apply it to a fashion sketch or croquis. You can create your own croquis and scan it into Illustrator, or you can use the one in the Pixel pattern library.

Start by creating a new artboard. Click the Artboard tool in the toolbar.

Click New Artboard in the Control panel. Place the new artboard on your canvas far away from your tile. Click the Presets menu in the Control panel and choose Tabloid. 

Press Esc to exit the Artboard tool.

In the Libraries panel, scroll to the Graphics section. Select the croquis thumbnail, hold Option, and drag it onto the new artboard. This allows you to place an editable version of the graphic.

Click in the open space of the artboard to deselect the entire croquis, and then click just its garment. Click the Fill option in the Swatches panel then click the new pattern you just created. 

Experiment with other textiles and croquis to create your own fashion collection.