Here are two methods that can be used In all versions of Altium Designer:
Method 1 (preferred), Direct Copy and Paste
Save your BMP image in monochrome using the Microsoft Windows Paint program. Select the MonoChrome option in the 'Save as type' section as shown:
In Microsoft Paint, press Ctrl+A and then Ctrl+C to select and copy your logo image.
Open your *.PcbDoc in Altium Designer. Select the layer on which you wish to paste your logo and press Ctrl+V. If you do not see the image appear, try pasting it into a new BMP in Microsoft Paint and then copy and paste again into Altium Designer.
To resize your imported logo, (the pasted image will come in as a union of all pasted objects):
Hover over the graphic you've pasted and right-click and select Unions ► Resize Union
Click on the Logo image and you should see handles appear at each of the corners.
Click and drag on a white edit handle at the corner to resize. NOTE: (It is important to let the image redraw before releasing your mouse or you might lose the entire image).
Copy the Bitmap image to a new Microsoft Word document.
Save the Microsoft Word document. This will automatically convert the image to an OLE object.
In Altium Designer, select the layer to place the logo on in your Pcb document.
Use the command, Place ► Object From File to place the OLE object into Altium Designer.
The image will retain its original size. It is necessary to edit the image in the Microsoft Document and resave it to update the image size in your PCB.
Note: If an error is encountered when using Place ► Object From File, "supported OLE Server was not found for file", it might be necessary to copy the image in the Word file and paste it into a new Word document file and save. Then try the OLE placement in Altium Designer using the new file
If you are using or can update Altium Designer to version 21 or newer, you may use the method described in this Knowledge Base article that allows for more file types to be more easily imported: Placing a logo into a PCB document