Hi
If you want to add a crossfade between 2 consecutive clips on the same track then Dougie's advice is correct.
Select clip1 by left clicking it. Now left click the transition tab on the toolbar and select Crossf Fade from the list.
Enter the duration (say 2 seconds) then the OK button.
The crossfade will appear over the thumbnails between the two clips as a yellow bar.
This may be satisfactory but depending on the amount of movement seen in the clips there may be a "still image" effect during the transition.
This can be removed by setting the IN/OUT markers for each clip as Dougie suggests but a simpler method is as follows....
First select clip1
Now grab the joint between the clips where it will turn into a double headed arrow. Drag the end of clip 1 to the left, back to the start of the yellow transition block line (A vertical yellow line will appear as this is done so you can see where you are)
Now select clip2. Grab the join again and drag the start of clip 2 along to the right hand end of the transition block.
The transition will now play without any still image effect.
You are in effect trimming the ends of each clip back . The sections being "trimmed" off are played during the transition.
Using the OUT marker on clip1 and the IN marker on clip2 achieves the same thing but is a little more fiddly.
If your clips are on different video tracks then a crossfade is slightly simpler. Note that the upper track will overplay the lower track and it is to this track that the transition (actually an effect) is applied. I am gong to assume that clip1 is on the lower track and clip2 is on the upper (overlay) track.
Select the uppermost clip and then click the Effects tab on the toolbar.
In the window that appears click "Add Effect" and select "Opacity" from the list.
Slide the opacity control fully to the left so it reads 0%
Click the Green cross to fix this value.
Grab the cursor bar by the blue blob in the level window on the right and drag it along about 2 seconds along the time bar.
Depending on the size of the clip you will have to estimate this distance or use the time markings visible over the box. (It can easily be readjusted later)
Now click the Green cross once more to set this value.
Don't move the cursor now
Drag the opacity fully to the right to show 100% opacity.
The blue line reflecting the opacity should now start at the bottom of the window and rise quickly (over a couple of seconds) to the top and then remain there for the remainder of the clip.
In effect what you have now done is to make the start of clip2 totally transparent but totally opaque after 2 seconds.
Click Close and you will see the effect on clip2 as a checquered thumbnail or two.
Now grab clip 2 and drag it left so that the checquered section is over clip1 on the lower track.
When the sequence is now played, clip2 will fade in over clip 1. If the intervals are not correct then its an easy matter to alter the points in the effect window or the amount of overlap beween the clips.
Nat