Open Photoshop 6.0 first. Create new file with 72 PPI fill the background layer with black.
Type one character each on separate layer. Make a duplicate layer of each character. Upper character should be bigger size and white. Lower character should be smaller size and blue or any color you like.
The file will look like this.

The layer palette of photoshop will look like this. Observe it carefully. Save your file.

File > Jump To > Image Ready 3.0
Image Ready 3.0 will get opened with the following File.

Animation palette of the file will contain following frame. Initially there will be only one frame.

Press 8th button from the bottom left which Duplicates current frame. Create six more frames. Total frames will be 7.

Select first frame. Here you need to display only black background. So in the layer palette of Image Ready, hide all the layers except background.

Select second frame. Here you want to display only big sized white colored 'F' with black background. So in the layer palette hide all the layers except White F and background.
Following is the position of the layer palette for the last 7th frame where only blue colored text is supposed to be displayed. Observe it carefully.

There is a small black triangle at the bottom of each frame in the Animation palette. It is used to set the time. Click it and set the time. You can select any number of frames at a time and set the same time for the selected frames.
Below the first frame there is a bigger black triangle used to set the looping of the animation. Use it to set the number of time you want to play Animation.

After completing the animation try to check the performance in the browser
File > Preview In > Click the browser you want

Save the file with
File > Save Optimized or File > Save Optimized As