Adapted from https://helpx.adobe.com/photoshop/tutorials.html

1. Combining images |
Applying filters

2. Add texture to an image
Start with two layers. The image with the texture you want to add should be on the top layer and the main image should be
the bottom layer.
In the Layers panel, make sure the top layer (texture) is selected.
At the top left of the Layers panel, change the blend mode in the drop-down menu from Normal to Overlay. This changes the
way the colors in the texture layer interact with the colors on the layer below. Try out some other blend modes to find the
one that looks best with your images.
At the top of the Layers panel, experiment with decreasing the Opacity slider to change the look of the texture of the image.

3. Add an object to an image with a layer mask
Start with two layers. The image with the object you
want to add should be on the top layer and the main
image should be the bottom layer.
In the Layers panel, make sure the top layer (object
you want to add) is selected.
At the bottom of the Layers panel, click the Add layer
mask icon. This adds a white rectangle or thumbnail
that is linked to your top layer. This white rectangle is
the layer mask. The layer mask determines what part
of the linked layer is visible and what part is hidden.
White on the mask represents areas that are visible.
Black on the mask represents areas that are hidden.

4. Replace a background using a layer mask
Start with two layers. The original image should
be on the top layer and a replacement
background image should be the bottom layer.
In the Layers panel, make sure the top layer
(original image) is selected.
In the Tools panel, select the Quick Selection
tool and use it to select all the areas in the
original image you want to keep in the final
output – everything except the background of
the original image.
A the bottom of the Layers panel, click the Add
layer mask icon. This adds a layer mask
thumbnail linked to the top layer. The layer
mask is hiding everything except what you
selected. The hidden areas on your top layer
allow you to see down through the layer stack
to the replacement background on your bottom
layer.

5. Browse the Filter Gallery
Select a layer that contains content you want to
change. Go to the menu bar and choose Filter >
Filter Gallery. Try the different filters and adjust
their settings for the desired result. Experiment
with adding multiple filters in the Filter Gallery and
changing their stacking order. Click OK to close the
Filter Gallery and apply the filters you chose. You
can also filter after you create a selection to apply
filters to only the selected area.

6. Blur an image with Smart Filters
Select a layer that contains content you want to blur,
like a background.
Choose Filter > Convert to Smart Filters. Click OK.
This converts te selected layer into a layer that will
support re-editable filters.
With the same layer selected, choose Filter > Blur >
Gaussian Blur.
In the Gaussian Blur dialog box, adjust the Radius
control until you’re happy with the amount of blur in
the live preview. Click OK to apply the Gaussian Blur
filter.
Note the Smart Filter that’s attached to your image
layer in the Layers panel. This allows you to flexibly
edit the filter settings. TO do that, double-click the
Gaussian Blur Smart Filter in the Layers panel, make
a change in the Gaussian Blur dialog box that
reopens, and click OK.
Save the image in Photoshop (PSD) format to retain
the Smart Filter layer.