Using Fotosizer...or "How I use Fotosizer Standard Edition"
This might also apply to other similar Foto editing software.Download and install the free Fotosizer Standard Edition...or buy the Pro Edition, its pretty cheap for a Lifetime License.
There are a few different versions, not sure how up to date mine is, but controls couldn't have changed too much.
Open the software to the main screen.
You can resize the Fotosizer window by stretching from the lower right corner.

The large gray area is for the photos you will be editing.
Literally drag images from any folder or anywhere on your computer, into the gray area.
You can also use the buttons at bottom left to add individual photos or entire folders.
Once you've added some photos, you will see a small thumbnail next to info about the photo.
Its location on your computer, its size and dimensions, its type...and the resize dimensions based on your settings.

You'll need to choose the desired resize setting for the photo(s).
I prefer 800px wide photos for web forum use.
This is the ideal size for visual impact, and compact forum use.
You can change the resize settings for each batch of photos, but some settings you can preset and not have to touch again.
Here are the settings I preset and leave in place:
Make sure to check the three options under the
Preset Size option.
These will keep your photos in proper ratio and shape.

Optional Settings is a drop down item...with three tabs.
Effects and
Rotation I don't touch.
Misc...make sure to change the quality to 100%.
By lowering this number, you will drastically reduce the file size. So this is great for very large photos.
But as you reduce the overall size of the photo, you want to keep a certain level of image quality or the photo will appear blurry and pixelated.
I opt for 100% quality for 800px wide photos.
Print DPI is what lowers the file size of the image. I usually stick with 96. Anything lower than 72 will give you a poor quality image.
Copy EXIF information...I leave unchecked to reduce file size
Copy XMP information...I leave unchecked to reduce file size

Destination Settings...another drop down...
Destination Folder is where the resized copies will be stored.
Photos are only copied. Originals are still there. Resize Copies are produced and stored wherever you specify. I usually just create them in the original source folder.
Output Formula should be jpeg for forum attachment use.
Once these settings are in place, they will not change from use to use.
You can of course make changes whenever necessary or desired.
When you are ready to resize your photo(s), just hit the
Start button (lower right) and wait for the process to complete.
Time to completion depends on the number of photos being processed.

Once finished, you can close the program or resize a new batch of photos.
Press the
Remove All button to clear the current batch of photos.
Navigate to the folder where you photos are saved and upload the ones you wish to use online.
Resizing your photos is not only necessary for attachment use,
but it can also save you valuable space at your online image storage site.
Photos that are reduced in data and dimension size will load and can be viewed much faster too!
if you need help with your photos, don't hesitate to ask.