Anyone could help.
After adding float for .lewa .prawa there no background

body {
    font-family: Georgia, Helvetica, Verdana, sans-serif;
    font-size:52%/1.52em;
    background-color: #fef8f8;
    background-image: url(../images/tlo.jpg);
    background-repeat: repeat-x;
}

#wrapper {
    height: auto;
    width: 960px;
    margin: 100px auto 10px;
}

#menu {
    background-color: #039;
    height: 48px;
    width: 780px;
    margin: -31px auto;
    z-index: 1;
}
#logo {
    height: 456px;
    width: 780px;
    margin: 31px auto 0;
    background-image: url(../images/hrabianka_logo.jpg);
    background-repeat: no-repeat;

}

#tlo_srodek {
    width: 960px;
    border: 1px solid #e74750;
    background-color: #f9d0d2;
    background-image: url(../images/tlo_srodek.jpg);
    background-repeat: no-repeat;
    background-position: 10px 10px;
    z-index: 2;
    height: auto;
    margin-top: 31px;
    margin-right: auto;
    margin-bottom: 0;
    margin-left: auto;
}

#frametext {
    width: 780px;
    margin-top: 12px;
    margin-right: auto;
    margin-bottom: 12px;
    margin-left: auto;
    clear: both;
}
.lewa{
    width: 472px;
    float:left;
}
.prawa{
    width: 288px;
float:right;
}

Read the stickie on clearing floats, should take care of it.

http://www.webmaster-talk.com/css-fo...you-clear.html