In the Templates tab, under Image objects Present, their are many arrow symbols, drag one on to the top of the clip/image/title object you want to add it to,
To resize and move and rotate the arrow, select the arrow object - indicated by yellow arrow in the image below and use the Size Position and Rotation effects.
You can also use an image of an arrow this should be placed on a track below the clip/image/title object you want to add it to.
However it must be either:
a png file with a transparent background
or
a png/jpg with a suitable solid colour background colour, eg red, green, blue, different to the arrow colour, for applying the Chromakey effect to.
Further to what @johnebaker mentioned, the arrow (object) will be grouped with the selected object. You can ungroup them and use the arrow object elsewhere and change the duration.
Thanks. I don't have any arrows in the Templates tab for some reason. I Googled and found some .jpg and .png ones and brought them into MEP and manipulated them for size and orientation.
I don't have any arrows in the Templates tab for some reason.
I notice you have the Plus version but I'm pretty sure that should include at least some of those arrows. When you originally installed the program did you also select the option under Help>Install additional content (or similar wording)?