This should get you. I used an image from the web that was the same size as the one you have. Go to the admin panel/appearance/customize. Upload your image in the "Graphics" section, and copy the url that it is assigned. Open the css tab, and scroll down below the base css to the edit css box. Copy the code below, and paste it there.Paste your image url into the background-image tag. Click on Save and your done.
.ow_sign_in_wrap form {
position: relative;
top: -126px;
}
.ow_sign_in_wrap h2 {
background-image: url("Put the url to your image here");
background-size: contain;
background-repeat:no-repeat;
position: relative;
top: -126px;
font-size:0px;
height: 146px;
}