i do not want the white bg on the logo and menu on the homepage,

To make the Transparent header background in WordPress education theme. 

Add the following CSS in wp-admin >> Appearance >> Customize >> Additional CSS

.is-stuck.header {
	background-color:#FFF !important;
}
.header {
	background-color:rgba(255, 255, 255, 0.34) !important;
}

After that please edit the page home or any and edit the Row of Slider. Give it margin top -110px

That will give you the transparent background WordPress education theme. 

The slider is really very slow, 

can you please help me to change the image and I need to add some more texts.

I have having issues wth the plugins, very slow .

Hi however you can install the plugin you want to use, but if you want to use Revolution slider better you learn a little more about plugin. Please watch this video https://www.youtube.com/watch?v=0tP0Vg1s-eE

I hope this would explain how you can use Revolution slider. Go to wp-admin >> Revolution slider, Edit the desired slider and there you can change backgrund images for each slide.